参考：白话经典算法系列之五 归并排序的实现
1 #include "stdafx.h"
2
3 //t[]在外部申请，以此避免在函数体内部反复申请数组的开销。
4 void merge_array(int a[], int left, int middle, int right, int t[])
5 {
6 int l = left, r = middle + 1, k = 0;
7 while(l <= middle && r <= right)
8 {
9 if(a[l] < a[r])
10 t[k++] = a[l++];
11 else
12 t[k++] = a[r++];
13 }
14
15 while(l <= middle)
16 t[k++] = a[l++];
17
18 while(r <= right)
19 t[k++] = a[r++];
20
21 for(int i = 0; i < k; ++i)
22 a[left + i] = t[i]; //mark!第一次忘记写left了。
23 }
24
25 void merge_sort(int a[], int left, int right, int t[])
26 {
27 if(left >= right) return;
28 int middle = (left + right)/2;
29 merge_sort(a, left, middle, t);
30 merge_sort(a, middle + 1, right, t);
31 merge_array(a, left, middle, right, t);
32 }
33
34 int _tmain(int argc, _TCHAR* argv[])
35 {
36 int array[] = {7,10,19,25,12,17,21,30,48};
37
38 int * t = new int[sizeof(array)/sizeof(int)];
39 merge_sort(array, 0, sizeof(array)/sizeof(int) - 1, t);
40 delete []t;
41
42 getchar();
43 return 0;
44 }
